Conventional door-closer can be used to automatically close an opened door. Such a door-closer includes a spring acting to close an opened door and a hydraulic cylinder filled with oil to slow the door-closing movement. When opening a door installed with such a door-closer, it requires a large force to counteract the resilience force of the spring in the door-closer, to thereby cause the tiredness of the door passer.
The present inventor has found the defect of conventional door-closer and invented the present recovering apparatus for the doors or the like.